Commercial kitchens are equipped to prepare food for large numbers of people in facilities such as restaurants, hospitals and the like. Such kitchens are typically equipped with one or more commercial duty cooking units capable of cooking large amounts of food. On such a scale, the cooking process may generate substantial amounts of cooking heat and airborne cooking by-products such as water vapor, grease particulates, smoke and aerosols, all of which must be exhausted from the kitchen so as not to foul the environment of the facility. Too this end, large exhaust hoods are usually provided over the cooking units, with duct work connecting the hood to a motor driven exhaust fan located outside the facility such as on the roof or on the outside of an external wall. As the fan is rotated by the motor, air within the kitchen environment is drawn into the hood and exhausted to the outside atmosphere. In this way, heat and cooking by-products generated by the cooking units follow an air flow path to the outside through the hood.
Since part of the cooking by-products is formed by minute particles of grease that have a tendency to stick to the plenum chamber of the exhaust hood, many exhaust hoods include a system to wash the plenum chamber and the exhaust duct periodically. These washing systems typically include a valve assembly provided between a water source and one or more outlet nozzles mounted in the plenum chamber. A timer is often used to create a wash cycle by opening the valve assembly for a predetermined time.
To conform to safety regulations, conventional exhaust hoods additionally include a fire detection system and a fire suppression mechanism associated with the kitchen exhaust hood designed to extinguish a fire within the vicinity of the exhaust hood. The fire detection system may include one or more fusible links, heat sensors, manual switches or any other form of fire detectors. Typically, the kitchen exhaust hoods include a fire suppression system that employs the washing systems used to clean them. However, some systems include more advanced fire suppression techniques. Typically fire detection system signals an electrically operated valve, such as a solenoid valve, to provide fire suppressant through a nozzle to the interior of the plenum chamber to extinguish the fire.
Once installed, the kitchen exhaust hoods and fire suppression systems are typically not altered, but are kept serviceable through routine maintenance. Unfortunately, routine maintenance can cause fire suppression devices to be removed from the system and not replaced properly. For example, routine maintenance could require the removal of a pressurized gas tank for testing. A failure to properly replace the gas tank after the maintenance can cause the fire suppression system to not operate as effectively. Additionally, the electrical wiring of the kitchen hood and fire suppression system has the potential of being unintentionally damaged. For example, the kitchen hood and fire suppression system could be unintentionally damaged during kitchen renovations, where a break in the signaling line between the fire detection system and the fire suppression system could result in the fire suppression system not reacting to the detection of a fire. Thus, there is a need to monitor the electrical connectivity and integrity of the kitchen hood and fire suppression systems and provide a means for providing a built-in redundant fire suppression system.